SERS probing of fungal HET-s fibrils formed at neutral and acidic pH conditions.

Spectrochim Acta A Mol Biomol Spectrosc

Department of Electrical and Computer Engineering, University of Alberta, Edmonton T6G 1H9, AB, Canada. Electronic address:

Published: March 2024

AI Article Synopsis

  • * A promising technique called nanoplasmonics utilizes engineered metal nanostructures to enhance light scattering for a more sensitive detection process, notably through surface-enhanced Raman scattering (SERS).
  • * The study applied SERS alongside confocal microscopy to analyze the fungal prion HET-s at different pH levels, revealing distinct spectral fingerprints that highlight differences in fibril structure and potential mechanisms linking pH conditions to SERS outcomes.

Article Abstract

Advances in precision medical diagnostics require accurate and sensitive characterization of pathogens. In particular, health conditions associated with protein misfolding require an identification of proteinaceous amyloid fibrils or their precursors. These pathogenic entities express specific molecular structures, which require ultra-sensitive, molecular-level detection methods. A potentially transformative technique termed nanoplasmonics employs electro-optical phenomena in the vicinity of specially engineered metal nanostructures. A signature application of nanoplasmonics exploits enhancement of inelastic scattering of light in specific locations near metallic nanostructures, known as surface-enhanced Raman scattering (SERS). We applied SERS complemented with confocal microscopy imaging for ultra-sensitive, non-invasive, and label-free characterization of the fungal prion HET-s (218-289) as a model for β-sheet rich amyloid structures. This characterization employed Au-coated dielectric supports as plasmonic substrates. After confirming the formation of HET-s fibrils at both pH 7.5 and 2.8 using negative staining transmission electron microscopy, we subjected the fibril-containing solutions to multimodal analysis using confocal microscopy and SERS. The SERS spectral fingerprints from all HET-s samples expressed vibrational markers for β-structure, unstructured backbone, and aromatic side-chains. However, relative intensities of major SERS bands were pronouncedly different for the two pH levels. We have analyzed potential origins of the most pronounced SERS bands and proposed hypothetical mechanistic models that could explain the observed SERS fingerprints from HET-s fibrils grown at pH 7.5 and 2.8.

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http://dx.doi.org/10.1016/j.saa.2023.123817DOI Listing

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